ENGLISH ABSTRACT: This thesis deals with the design and evaluation of a 300 kW double stage axial-flux
permanent magnet generator with an ironless stator. The magnetic and electrical
design equations are derived for sinewave and quasi-squarewave axial-flux permanent
magnet machines. The thermal design approach used is also described. The machine
is optimised for maximum torque per current loading. A Matlab program code is
developed to do the necessary calculations in the design optimisation and the
calculation of the machine parameters.
Mechanical finite element simulations are conducted to investigate the severity of the
magnetic attraction force between the rotor discs. The results obtained from the
simulations suggested an increase in the yoke thickness in order to withstand the
attraction force. The construction of the prototype machine's rotor and stator is
described. The flux density in the airgap is thoroughly investigated through
measurements and analysis. Thermal measurements are also conducted to investigate
the effect of eddy currents in the stator winding. Furthermore, no-load measurements
conducted on the 300 kW machine showed that the machine has a serious problem of
circulating currents in the parallel connected coils. Possible solutions for this are
investigated and recommendations are given. Due to the circulating current problem
and the relative high eddy current losses, it was not possible to do full-load tests on
the machine.